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Electromagnetic Fidget Spinner Accelerator

Fidget Spinners are little plastic toys with a bearing in the center. They are fun for a little bit, but get boring after a while due to their slow spinning speeds. There are ways to make them spin faster, but these methods involve using a bulky air compressor or an expensive can of compressed air. Luckily, I have found a cheap way to accelerate these fidget spinners to extremely high speeds with the power of electromagnetism. You can even hold the spinner in your hand while you accelerate it! I have clocked a spinner that is spinning with this accelerator at speeds up to 1440 RPM, that is fast. You can build this accelerator too, it is really cheap and really simple to build.

Step 1: How It Works

This fidget spinner accelerator works by using an electromagnet with a reed switch and a fidget spinner with magnets mounted on the 3 sides. First of all, the magnets on the fidget spinner are mounted so that all the magnets have their north pole facing outwards. The electromagnet is wired so that the side that is closest to the spinner will have a north polarity when it is powered. When the spinner starts spinning (Refer to the above diagram) the electromagnet will be off. As the magnet on one side of the spinner passes the electromagnet, it will trigger the reed switch, activating the electromagnet. Because both magnet and electromagnet will now have the same poles, that arm of the spinner will be pushed away from the electromagnet. When it moves far enough away, the reed switch will disengage and shut off the electromagnet. Because the spinner will be spinning from this first cycle, it will have enough momentum for the next arm to move past the electromagnet and reed switch and repeat the cycle. As each arm moves by the electromagnet and get repulsed, the spinner will speed up and gain momentum. That is how this system of acceleration works!

Now, for how the circuit works. The reed switch alone cannot handle the high currents that the electromagnet draws, so it will need a buffer between it and the electromagnet. This buffer will be a MOSFET transistor. When the reed switch is triggered, it will let current flow from VCC to the gate of the MOSFET. This will allow current to flow form VCC, though the electromagnet, into the drain of the FET, and out of the source back to ground. The diode on the electromagnet is called a flyback diode, and its purpose is to absorb all the excess energy created by the collapsing magnetic field of the the electromagnet. Without it, the MOSFET would potentially be fried. The resistor from the gate of the MOSFET to ground serves to drain the excess charge from the gate after the reed switch turns off. Because the gate of the FET has capacitance to the source, this means that even after you remove power form the gate, the MOSFET will still be on, causing the circuit to constantly be on. The resistor prevents this.

Step 2: Materials

For this project, you will not need very many materials. You will need:

A 3 arm Fidget Spinner(Well Duh)

Small Ceramic Magnets

A piece of perf-board

An N Channel MOSFET(Almost any one will work)

A magnetic Reed Switch

A 10k resistor

An inductor (More information in step 5)

A 1n4004 diode

Wire

Terminal connectors

12 Volt Power Source (Batter or bench power supply)

Step 3: Tools

For this project, the tools you will need are:

Hot Glue Gun

Soldering Iron

Wire strippers/cutters

Hacksaw

Optional:

Oscilloscope

Step 4: Setting Up the Spinner

To set up the spinner, you will just need to take three magnets, and hot glue them to the three arms of the spinner. Now, when you attach the magnets, make sure that the same side, or pole, of each magnet is facing out. This means that after you are done gluing them in place, you should be able to take another magnet, and hold it to all the magnets with the same side, and get the same reaction. In my case, there was an indentation on the north pole of the magnet, so all the indentations faced outwards.

You will also need to make sure that you use the same amount of hot glue for each side. If you do not, then your spinner will be unbalanced. It is also important to use a lot of glue, if you don't, then a magnet might fly off due to centrifugal force, also known as tangential velocity. This might cause, I don't know, maybe a dent in the wall? (I know from experience. Haha). It will also cause your spinner to become unsafe. Now, it is time to start building your circuit!

Step 5: Choosing an Inductor

The inductor is one of the most important parts of this project, it acts as the electromagnet that makes the spinner spin. This means that you will have to find the perfect inductor. You can start by digging through your parts drawers of inductors. You will first need to find an inductor that has the perfect resistance, and is not magnetized. Some inductors are magnetized, and these will not work, so before using one, hold it up to a piece of metal. If it sticks, don't use it. You also need to find an inductor with the right resistance. To high of a resistance, and the feild will not be as strong. To low of a resistance, and it will draw too much power. My inductor came out of an old TV board. It is 2.9 ohms and 5.82mH. Make sure that the inductor you choose is made of a ferrous material.

To test your inductor, set you fidget spinner down, and connect the inductor to a power supply. Then, tap the power supply leads on and off the inductor pins while moving it near the spinner. It should cause the spinner to spin! You may have to go though some experimenting to find the right inductor for your project.

Step 6: Cutting the Perf-board

The perf-board is what holds all the components of the EFSA. You will need to cut it so it is large enough to hold all the components for your accelerator, but not too big. You will also need to cut a triangle off of one end to hold the inductor. I made all the cuts in my perf-board with a hacksaw.

Step 7: Soldering the Circuit

This is one of the most difficult parts of this project. You will need to follow the circuit diagram to solder all the parts of the board in place. The positions of the reed switch and the inductor are very important. The reed switch needs to be far enough away from the inductor so that the magnetic field will not cause the circuit to self trigger, but close enough to make the circuit run as efficiently as possible. You will need to do a little experimentation to find this sweet spot. I used screw terminals to connect the inductor and the power wires to the board. You will need to make sure that all the connections shown on the circuit diagram are soldered on the perf-board in real life. Look at the pictures closely to find further know how to solder this board. When you are done soldering the accelerator board, then you should be ready to test it!!

Step 8: Power Supply

This fidget spinner accelerator needs a power supply that can provide 12 volts at 1.5 amps. This power draw will change based on the specs of the inductor you use as an electromagnet. If you just want to use this accelerator at your desk, then you can just connect it to a good bench power supply or computer power supply. If you want to make it portable, then you can use a LiPo or LIon battery. To find out how to make your own 11.1 volt LIon battery, check out my instructable and YouTube video below.

Step 9: Finding the RPM

To measure the RPM of this fidget spinner, all you need is the accelerator and an oscilloscope. First of all, you will need to connect the probe of the scope to the gate of the mosfet. This pin will be high 3 times per revolution because the magnets on each arm of the spinner will trigger reed switch each time they pass it. Then, ground the oscilloscope to the ground of the accelerator. Finally, get a friend to use the fidget spinner accelerator while you look at the oscilloscope. After the spinner was up to full speed, the scope registered a frequency of 72 Hz. This means that magnets were passing the reed switch 72 times per second! You can divide this number by three to find the rounds per second, which would be 24. You can then multiply the RPS by 60 to get the RPM: 1440. This fidget spinner accelerator really makes the spinner spin fast.

Step 10: Have Fun!

To use your spinner with the accelerator, simply hold the spinner with one hand and the accelerator in the other, then give the spinner a little jump start. After that, hold the accelerator closer to the spinner without touching it, and you should see it start to accelerate! The closer you hold the accelerator, the faster it will go!

This device is really a lot of fun. It is especially cool to feel the gyroscopic effect of the spinner at these high speeds. You can also impress your friends by spinning your spinner faster than any of them can. The Electromagnetic Fidget Spinner Accelerator turns a regular old fidget spinner into a truly awesome toy.

Thanks for reading and good luck building! Also, remember to vote for me in the contests!

A couple of ideas.....rather than glue magnets to the end of the fidget spinner arms, where they could fly off at high speed, find a spinner which can fit neodymium magnets and squeeze them in. I found a 5-arm spinner which had large ball bearings near the ends. These could be popped out, and the 10mm diameter magnets fitted tightly in the spaces. The magnets need to have their S or N pole sides all facing up in the same orientation.

See photo.

I also changed the reed switch for the A3177 Hall Effect sensor, which allows faster rotation of the spinner. See circuit diagram.

A hall-effect sensor would be a big improvement over a reed switch. Once you overcame the limit of having a mechanical switch, it could theoretically accelerate until the air resistance (drag) equals the force applied by the electromagnet, causing a net force of zero and therefore no acceleration. That is, assuming there wasn't any other bottleneck component like the speed of the transistor.

This is a fantastic project and I think it has the potential of educating my boys in a number of ways. My problem is that I don't have a "drawer of inductors". Can you recommend a model/part that I could find on Amazon or at Micro Center?

This is fantastic. It was exactly what I was looking for to impress my grand kids. Is anyone interested to build it for me for $$, as I don't have the expertise to find all the components to build it. Or can you tell me where to buy the components?

I'd love to see what would happen if you swapped the reed for a Hall effect switch. Maybe the mechanical actuation time is what's limiting it so far. 120hz+ seems like asking a lot of the poor reed switch.

Would be neat to actuate it with a micro and PID loop, maybe even display the RPMs and control with a pot/buttons!

Great project! Love your lab. Based on the photos and video, you really seem to be talented and know what you're doing (rare). Reminds me of my setup about 50 years ago when I started designing projects. All with vacuum tubes, and I was happy as a bunny when the first transistor was actually available for buying.

One small comment re one of your descriptions (think about it and the physics will make perfect sense):

You say when talking about gluing the magnets "then a magnet might fly off due to centrifugal force, also known as tangential velocity". What really happens if the glue lets go is the magnet flies off " in the direction of the instantaneous tangential velocity". The glue exerts a centripetal force on the magnet keeping it locked going toward the centre of the spinning system. Centrifugal force is a fictitious never-ending historical misunderstanding. If the glue breaks the magnet travels, as you say correctly, tangentially. If centrifugal was real, the magnet would fly in a radial direction outward. Never happens, try it!

Well, not really. It depends on your frame of reference. If you are standing still outside the rotating body, there is no centrifugal force, it's just radial acceleration and the weight will fly off tangentially.

However if you are standing inside the rotating body, your frame of reference is rotating with the body and centrifugal force is real. As a matter of fact, if you release a weight, it will fall down towards your feet not tangentially because your frame of reference is moving. (for short distances only because your frame of reference is curving but the weight is moving in a straight line - coriolis effect - that's what causes hurricanes and tornadoes)

You're mixing a lot of things together that tends to make the basic idea fuzzy. Ignore gravity, falling on your toes (ouch) and hurricanes. Frames of reference do not change the basic concept and physics of the system. Centripetal implies seeking the central point of the motion and centrifugal says the object is trying to get away from the centre. An analysis of any rotating system, be it a ball on a string or an orbiting planet held by gravity, will show a force vector that is always pointed toward the centre of motion. It feels like the ball is pulling on the string and wants to get away from the centre but in reality it's the string that is pulling on the ball to keep it rotating since it really wants to keep going straight (tangentially). The string pulling on the ball or gravity pulling on the planet are the only forces involved in the math.

Remember the old " every action has an equal and opposite reaction" ?Centrifugal is a name for an opposite reaction to the real centripetal action the keeps the object moving in a nice circle around whatever the centre is. Cut the string, the reaction disappears and the object keeps moving in a straight line. Sorry for the long-winded story.

Ok, fuzzy and off topic, but while a moving frame of reference does not change the physics, it does change the math needed to represent the physics. It also changes the apparent motion you think you see if you are inside the moving frame of reference.

Coriolis force/effect is an explanation for why something does not move in apparently straight lines inside your moving frame of reference.

Centrifugal force is not fictitious, it is merely a description of apparent forces inside a moving frame of reference. (and besides, nobody can define the non-moving center of the universe, so all frames of reference are moving - you just pick one that makes your math easiest)